Disorders of the anterior attentional-intentional system in patients with end stage renal disease: Evidence from reaction time studies

Hemodialyzed Individuals' Left Spatial Attentional Bias Is Normalized Following Successful Kidney Transplantation

BACKGROUND

Healthy people have a leftward spatial attentional bias, called pseudoneglect. Individuals with end-stage renal disease (ESRD) who are receiving hemodialysis often demonstrate an increase in their leftward spatial attentional bias. Whereas a successful kidney transplant often improves the cognitive functions of individuals who previously received hemodialysis, the effect of a kidney transplant on this abnormal allocation of spatial attention has not been investigated.

OBJECTIVE

To investigate the effects of kidney transplant on individuals who were being treated with dialysis and had an increase in their left spatial attentional bias.

METHOD

The performance of 20 hemodialyzed individuals with ESRD on the line bisection test was compared to that of 17 demographically matched individuals with ESRD, who had received a kidney transplant, and 23 demographically matched healthy controls (HC).

RESULTS

All of the participants exhibited a left spatial bias on the line bisection task. When compared with the HC, the hemodialyzed individuals demonstrated a significantly greater left spatial bias. There was, however, no difference in spatial bias between the HC and the individuals who had received a kidney transplant.

CONCLUSION

A successful kidney transplant can improve patients' abnormal leftward allocation of spatial attention. However, future studies are needed to better understand the mechanisms of this spatial attentional bias in hemodialyzed individuals and the normalization of bias following transplantation.

The Allocation of Vertical Attention in Patients with End-Stage Renal Disease Receiving Dialysis

Objectives: Alterations of spatial attention can have adverse effects, such a greater probability of accidents. Patients with end-stage renal disease (ESRD) receiving dialysis have stronger left-sided spatial attentional bias, suggesting that this disorder or treatment alters the brain networks that mediate spatial attention. The hemispheric networks that mediate the allocation of horizontal attention may also influence the allocation of vertical attention. However, the allocation of vertical spatial attention has not been studied in ESRD patients. Methods: Twenty-three ESRD patients receiving dialysis and 23 healthy right-handed controls performed line bisections using 24 vertical lines (24 cm long and 2 mm thick) aligned with the intersection of their midsagittal and coronal planes. Results: Hemodialyzed ESRD patients had a significantly greater upward bias than healthy controls. The magnitude of this bias was correlated with the duration of the kidney disease. Conclusions: The reason why upward attentional bias is increased in hemodialyzed ESRD patients is not known. Further research is needed to better understand the brain mechanism that might account for this bias, as well as its treatment. However, hemodialyzed ESRD patients and their families-caregivers should be made aware of this disorder to avoid accidents such as tripping.

Kidney transplantation and action-intentional improvements: Evidence from an ERP study

Reaction slowing observed in dialyzed patients results from deficits in initiating and sustaining motor response mobilization. The present study aimed at investigating whether these deficits are reversible following successful kidney transplantation. To achieve this goal, behavioral and electrophysiological (EEG) data were assessed from healthy control participants as well as kidney transplant and dialyzed patients performing a series of reaction time tasks. The results demonstrated that in patients who received kidney transplant a normalization of response latencies and brain preparatory activity was observed. At the same time, when compared to healthy individuals, increased attention engagement was observed in both clinical groups of patients. No behavioral and electrophysiological indices of impaired monitoring were observed in any of the clinical groups.

The Anterior Attentional-Intentional System in Patients with Parkinson's Disease-A Pilot and Feasibility Study

(1) Background: This study compared anterior attentional–intentional system performance between three groups: Parkinson’s disease (PD) patients with normal cognition (PD-NC), with mild cognitive impairment (PD-MCI), and a comparison group (CG). It also evaluated the feasibility of the recruitment and study procedures; (2) Methods: From 45 participants recruited, 39 were allocated (mean age 65.31; 43.59% men) to PD-NC, PD-MCI and CG (13 per group). To assess attention, we used three tasks from the ROtman–Baycrest Battery for Investigating Attention: Simple Reaction time (RT), Choice RT, and Prepare RT. We conducted a mixed-model analysis of variance with a 3 (groups) × 4 (tasks) design to compare reaction times; (3) Results: PD-MCI had slower reaction times than PD-NC (p = 0.028) and the CG (p = 0.052); there was no difference between PD-NC and CG. PD-MCI might perform worse on monitoring tasks than PD-NC, Z = −1.68, p = 0.092. Nearly half the volunteers from the CG and 87% of all eligible patients were enrolled in the study and completed all neuropsychological procedures; (4) Conclusions: General cognitive decline appears related to partial deficits in energization and tends to impair attentional monitoring. Furthermore, PD-NC exhibited similar reaction times to the CG. Results from the feasibility study contributed to the definitive study.

Ineffective initiation contributes to deficient verbal and non-verbal fluency in patients with schizophrenia

AIMS

Patients with schizophrenia (SCH) show impaired verbal and non-verbal fluency. However, these individuals' fluctuations in words or designs generation efficiency over time, a phenomenon that may significantly affect fluency, have never been studied. Thus, the aim of this research was to investigate if individuals with SCH may present with alternations in the dynamics of the information production and its control as well as to test if the potential abnormalities in this regard might affect these patients' overall performance on both verbal and non-verbal fluency tasks.

METHOD

Forty-four patients with SCH and 40 healthy controls (HC) completed both verbal (phonological, semantic) and non-verbal fluency tests. To analyse processing efficiency changes over time, the period in which subjects had to generate words or designs (60 s) has been divided into 15-s sections.

RESULTS

In comparison to HCs, individuals with SCH obtained significantly lower total scores for all fluency measures. Furthermore, group differences in the dynamics of the test performance also emerged, with SCH patients having a significantly worse production during the initial 15 s of each fluency task. Additionally, the initial production deficiency seen in patients with SCH has accounted for these individuals' total performance. Moreover, comparisons of errors distribution over time during the phonemic and figural fluency performance also revealed differences, suggesting there was a rapid depletion in maintaining of cognitive control in the SCH sample.

CONCLUSIONS

Inefficient fluency in SCH may arise from a more general initiation deficits that may partly account for these patients' cognitive problems.